A projected capacitive touch panel is implemented based on a traditional capacitive touch panel and further includes two sets of transparent wires (X and Y) implemented on two different planes and perpendicular to each other and a plurality of driving wires. A conventional projected capacitive touch panel and a fabricating method thereof are described as follow.
Please refer to FIG. 1, which is a flow chart schematically showing the conventional fabricating method for a traditional projected capacitive touch panel. The steps of the conventional fabricating method 100 are illustrated as follow.
(Step 101) A glass substrate is provided.
(Step 102) A first Indium Tin Oxide (ITO) layer is formed/sputtered on the glass substrate. A coating process, an exposing process, a developing process, an etching process, and a stripping process are sequentially proceeded with some sort of photo-resist (A) on the ITO layer so as to form an x-axis pattern layer (including an x-axis channel) acting as a first conductive layer. It is noted that a first photo mask is used in the step.
(Step 103) A coating process, an exposing process, a developing process, an etching process, and a baking process are sequentially proceeded with some sort of photo-resist (B) on the first conductive layer so as to form an insulating layer acting as an insulating film between the x-axis channel and an y-axis channel for insulating the x-axis pattern from an y-axis pattern. It is noted that a second photo mask is used in the step.
(Step 104) A coating process, an exposure process, a development process, an etching process, and a pre-baking process are sequentially proceeded with some sort of photo-resist (A) on the insulating layer. Then a second ITO layer is formed/sputtered thereon and a stripping process is performed to form the y-axis pattern layer (including the y-axis channel) as a second conductive layer. It is noted that a third photo mask is used in the step.
(Step 105) A metal layer is sputtered on the second conductive layer. A coating process, an exposing process, a developing process, an etching process, and a stripping process are sequentially proceeded with some sort of photo-resist (D) on the metal layer so as to form a metal trace layer. It is noted that a fourth photo mask is used in the step.
(Step 106) An Asahiksei Photosensitive Resin (APR) material is printed on the metal trace layer and then solidified with UV light, so as to be transformed into the top-coating (TP) layer. Finally, the above half-finished projected capacitive touch panel is electrically detected and then cut into a finished projected capacitive touch panel.
Please refer to FIG. 2, which is a schematic diagram showing the layers of a traditional projected capacitive touch panel made by the conventional fabricating method of FIG. 1. In FIG. 2, the projected capacitive touch panel 200 includes sequentially a glass substrate 201 as a substrate, an x-axis pattern layer 202 as a first conductive layer, an insulating layer 203 as an insulating film between the crossing point of the x-axis pattern and an y-axis pattern, the y-axis pattern layer 204 as a second conductive layer, a metal layer 205 as a metal trace layer, and a top-coating layer 206.
Please refer to FIGS. 3(a) to 3(i), which are structural and cross-sectional drawings of a traditional projected capacitive touch panel corresponding to the conventional fabricating method of FIG. 1. In FIG. 3(a), an x-axis pattern layer 302 (including an x-axis channel) as a first conductive layer is formed on a glass substrate 301. The x-axis pattern layer 302 has a plurality of rhombic patterns and a plurality of x-axis channels to respectively connecting each of the rhombic patterns. The material of the x-axis pattern layer 302 is ITO. FIG. 3(b) is the cross-sectional drawing of the cross-section A-A′.
In FIG. 3(c), an insulating film 303 as an insulating layer is formed on the x-axis channel of the x-axis pattern layer 302. FIG. 3(d) is the cross-sectional drawing of the cross-section B-B′.
In FIG. 3(e), a y-axis pattern layer 304 (including a y-axis channel) as a second conductive layer is formed on the glass substrate 301 and the insulating film 303. The y-axis pattern layer 304 has a plurality of rhombic patterns and a plurality of y-axis channels to respectively connecting each of the rhombic patterns. The material of the y-axis pattern layer 304 is ITO. It is noted that the insulating film 303 is deposed between the x-axis channel and the y-axis channel for insulating the x-axis pattern layer from the y-axis pattern layer. FIG. 3(f) is the cross-sectional drawing of the cross-section C-C′ and FIG. 3(g) is the cross-sectional drawing of the cross-section D-D′.
In FIG. 3(h), the connection of the x-axis pattern layer 302 and metal traces 305 is shown. FIG. 3(i) is the cross-sectional drawing of the cross-section E-E′.
It is noted that the previous Application (application Ser. No. 12/559,624) submitted by the Applicant teaches another method. The method includes providing a substrate, forming a metal trace layer on the substrate, forming a first pattern layer on the metal trace layer, forming an insulation layer on the first pattern layer and forming a second pattern layer on the insulation layer.
The above fabricating method for the traditional projected capacitive touch panel has the following drawbacks:
(1) There are apparent patterns appeared. The color/chromaticity discrepancy between the x-axis pattern layer and the y-axis pattern layer causes the appearance of the apparent rhombic patterns. In the two sputtering process, the difference of the oxygen quantities, the difference of sputtering temperature, the difference of sputtering time and the difference of the consuming of ITO target would cause the chromaticity of the ITO films different after sputtering, because the x-axis pattern layer and the y-axis pattern layer are not formed/sputtered at the same time. It is noted that, due to the thinness of the ITO, the thickness of the ITO films are difficult to control so as to result in the color discrepancy between the x-axis pattern layer and the y-axis pattern layer easily.
(2) The following stripping process may not be performed. It is because the photo-resist suffers from the high sputtering temperature of the second sputtering process and then turns solidified.
(3) The externals (appearance/looks) of the prior art are defective. The reason is that, in consideration of simplifying the process, the bridge point is formed by using the metal traces and it shows shiny spots which can be detected by humans' eye.
Therefore, it would be useful to invent a digital photo frame to circumvent all the above issues. In order to fulfill this need the inventors have proposed an invention “PROJECTED CAPACITIVE TOUCH PANEL AND FABRICATING METHOD THEREOF.” The summary of the present invention is described as follows.